Method of multiple cold reducing strip metals



Patented Nov. 28,

UNITED STATES PATENT OFFICE Y METHOD F MULTIPLE COLD REDUCING STRIP METALS Howard s. on, am, 1nd.-

Applicauon January 21, 1937, serial No. 121,641

2 Claims.

The present practice in tension strip rolling mills is to reduce the strip as a single ply or thickness within the close nal thickness tolerances demanded by the trade. Thus, for example, in rolling tin plate stock the initial strip is reduced from about .065 inch down to about .010 inch thickness with a resultant thickness Variation of not over plus or minus .0005 inch. In some cases this tin plate stock must be held to a gauge variation of plus or minus .00025 inch.

To obtain such a iinal exacting gauge tolerancep it has not heretofore been possible to roll such strip metal in single ply wider than approximately 30 inches. In the reduction under tension of automobile body stock and the like, a strip oi' single thickness is reduced from about .100 inch to about .038 inch with a resultantthickness tolerance around plus or minus .002 inch. Strip of this nal and 26 single thickness could be rolled as wide as apstrip and suiiiciently wide reducing mills arel available.

An object of this invention is to provide a 30 method of rolling, as a single strip under tension, two or more superimposed thicknesses of strip metal of substantially the same analysis, thereby increasing the output of the mill in 'proportion to width and/or 'thickness Without affecting operating speeds on the same reducing mill over the same material as rolled in single ply thickness.

Another object is to provide a method of rolling as a single strip, under tension, multiple thicknesses of extremely wide and thin gauge 40 metals, whereby the width of metal rolled may be increased in proportion to the'number o! superimposed multiple thicknesses, with a resultant single thickness variation, of any one of the superimposed strips, comparable to thesame resultant thickness variation in lesser widths as rolled singly. These and other objects will become apparent the description proceeds, in which: The gure illustrates a single stand reversing cold reduction mill wherein hot rolled and pickled strip metals in two or more superimposed thicknesses are reduced to the desired gauge.

Hot rolled and pickled strip is preferably coiled on lreels preparatoryto carrying out the reduction under my present method. The reduction in a tension mill of this strip metal necessarily includes the superimposing of two or more of these strips on one another so that the strips may either be fed singly up to the mill and superimposed immediately beiore being reduced in multiple, they may be superimposed on one another onto a single reel, which latter case is preferred. l In either event, it is quite imperative that the` different strips that are to be superimposed be of approximately the samegauge or thickness lil and of about the same width. In the event that one strip is longer than'the other, I nd it expedient to secure one end of two or more strips together thus allowing the other end of the strips to possibly extend one beyond the other. Any 15 excessive length ofv any one strip over the others is accordingly utilized as a single ply leader strip of the multiple strip coil end which leader strip is fed into and between the reducing'rolls and suitably attached to the winding or delivery 20 means.

Thus by way of example only, I may utilize a conventional four-high reversing cold reduction mill, as shown in the figure, wherein single ply hot rolled and pickled strips 2 and 3 are super- 25 imposed on one another to form a multiple strip. O ne end of both of the strips 2 and 3 are welded or otherwise secured together, as shown at 4, while the other end is secured at Ill to the unwinding reel 6. In this case, the excessive length 30 of the strip 2 is secured, at 5, to the winding reel 9 and acts as the leader'as previously described and is cut oi upon the completion o f the reduction of the multiple strips.

The superimposed strips 2 and 3 are fed into a 35 cold reducing mill which, for example, comprises a pair of work rolls 1 driven in any suitable manner (not shown). These rolls 1 are backed i up by large diametered rolls 8. The superimposed strips are fed from the unwinding reel 6 l4() over the guide roll l2 between the reducing rolls 'I to the winding or delivery reel 9 after passing .over a guide roll l2. The. multiple strip is tensioned to any desired degree between the two oppositely disposed reels 6 and 9 and the reduc- 45 A More speciiically and by way of example, my method of rolling as a single strip, under tension, two or more superimposed thicknesses of strip' metal increases output of the same mill 50 more or less proportionate to the increased width and thickness over the same material as rolled in single ply thickness.

Thus'the present method is to roll .060 inc h thickhot rolled and pickled strip down to .010

Table A.

Rolling 3o man by .oso inch not strip to .011 inch in three passes:

Max. Min. Length, Ave. Pass Ga speed, per

se met lt..min. speed pass Total time lor rolling 15. 50

Min. per coil=15.5+2.5 min. for changing coils=18 min. Weight per coil=5,000 pounds,

Table B Roumg three-ply 60 inch by .06o inch to .011 inch in three passes:

. Ave. Mln.

Length Pass Gauge speed per eet it. min. pass Total time for rolling 24. 21

pounds by 6=30,000 pounds, nished weight.,

Theoretical tonnage per eight-hour turn:

In Table B, it is to be noted that the increase of strip width has been doubled (i. e., from 30 to 60 inches). It is entirely possible to increase the width of metal being rolled in proportion to the number of superimposed thicknesses, the only factor to be considered being the ability to produce such wide Widths and thicknesses of hot rolled strip and mills of sucient width to handle such multiple thicknesses.

Regardless of the number of superimposed thicknesses, each of the strips will be reduced proportionately to their initial thickness and the resultant gauge variations will be within narrower limits in relation to the number of strips utilized. In any event, the resultant thickness yariations of any one strip will be within and much less than the variations of a single strip rolled singly and of the same width.

It is necessary in both my method of multiple strip reduction under tension, as well as in the present practice of reducing single ply thicknesses of strip metal, that the gauge from edge-to-edge of the nished cold reduced strip be held to within tolerances even less than that demanded for'cnh 'Y sible to hold the edge-to-edge gauge tolerances.

By my method, I am able to overcome this difculty and cold reduce, under tension, two or more thicknesses of superimposed strip which in widths land single thicknesses is in excess of 3000:1 and still obtain the end-to-end and edgeto-edge gauge Variations as demanded by the trade. I

Thus, from the foregoing description it will be readily appreciated that in single ply rolling, the narrower the width of metal, the greater the accuracy of the final gauge can be controlled (see I and III of Table C). It necessarily follows that in the reduction, under tension, of two or more thicknesses of the same width of metal the inaccuracies of gauge are equally divided between the number1 of strips which go to make up the multiple strip, providing that the initial gauge of all superimposed strips prior to reduction are comparable (see II of Table-C).

If the gauge variation of multiple rolling of superimposed strips is kept Within the gauge tolerance produced on single ply rolling, it is possible to utilize greater Widths in proportionate increase to the number of superimposed strips (see IV of Table C). Thus, I can obtain the same gauge tolerance in a 60 inch Wide strip as in a 30 inch wide strip if I utilize two superimposed strips or the same gauge tolerance of a single strip 90 inches wide as in a 30 inch Wide strip'if I utilize a multiple strip of three more or less equal thicknesses.

If I desire to increase the width in my multiple rolling without necessarily increasing it in proportion to the number of thicknesses or plies, I may improve the accuracy of the iinal gauge to well within the tolerances demanded and usually secured on a single ply thickness as many times narrower as the plies or thicknesses which I utilize (see V of Table C), with the additional advantage of tonnage output (see Table B).

Table C Ratio as Gauge in relarolled tion to Symbol vWidth Gauge Ply width commercial to thick acceptable ness tolerances 30" 010 Single. 3000:1 Acceptable. 30" .020 Double.. 150011 Well within. 60" 010 Single. 6000: l Well without. 60" 020 Double.. 3000: l Acceptable. 60" 030 Triple 2000: 1 Wlthm.

same degree of reduction thus producing the same proportion of 1mi-.iol to anal gauge' in -eaoh and every ply. This is made possible because in rolling 1 under tension, the tension distributes itself among the number of plies in direct proportion to the resistance set-up to reduction of the individual strips.

By my method of reducing, under tension, l

strip-like metals in multiple thicknesses I am able to obtain at least one good surface on each ply which is free from such supercial surface marks as stains, grease and oil deposits, and blemishes such as scratches, carbon pits, and marks due to irregularities in the contact surfaces of the rolls. Such a surface is extremely conducive to coating as by tin, lead, zinc, chromium, and the like.

Depending on the initial surface of the contacting rolls, various degrees 'of surface finish are possible on the multiple thickness'reduction, under tension, of strip metal. For example, two smooth contact or work rolls will produce, on low carbon strip in multiple thickness, a uniformly y dull but lustrous surface on the inner surfaces of all plies with the outer roll-contacting surface being necessarily bright and smooth. It follows that with one smooth and one rough contact roll or two rough contact 'rolls varying resultant surfaces may be produced.

surfacing as temper rolling it presents an excellent surface for coating as by tinning.

While I have shown and described a specific embodiment of the present invention, it will be understood that I do not wish to be limited ex-l actly thereto since variousfmodiiications may be made without departing from the scope of the invention as defined by the following claims.

-I claim:

1. In a method of cold rolling, as a single thickness, multiple thicknesses of strip-like metals the steps which include superimposing two or more strips of substantially the same width t and thickness upon each other, reducing under parable to a like strip rolled singly and of lesser Width.

2. In a method of cold rolling asa single vthicknessymultiple thicknesses of strip-like metals the steps which include, super-imposing two or more strips of substantially the same width and thickness and of varying hardness upon each other, reducing under tension the superimposed strips between a pair of reducing rolls to decrease the final thickness gauge to1er' ances in direct proportion to the number of plies when compared to a single ply rolled singly of the same initial metal, the width of said strip capable of being increased in proportion to the number of superimposed thicknesses, each of which has a resultant thickness variationcomparable to a like strip rolled singly and of lesser Width.

HOWARD S. ORR. 

